Health Library

Ataxia Telangiectasia (A-T)

Ataxia telangiectasia (A-T) is a rare inherited childhood disease that affects the nervous system and other body systems. The effects of A-T usually begin to appear by the age of 5 in a child affected by the disease.

What causes A-T?

A-T is caused by mutations in a gene on chromosome 11 known as the ATM gene, which is involved in cell cycle control. This neurodegenerative disorder is inherited in an autosomal recessive fashion, which means that two mutated ATM genes are necessary to produce the condition--one inherited from each parent. People with only one ATM mutation are referred to as "carriers."

Some studies suggest that people who are carriers of an ATM mutation are at an increased risk to develop breast cancer. It is estimated that about 1 percent of the U.S. population, or about 2.5 million people, may be carriers for an ATM mutation. This may lead one to believe that many people with breast cancer develop it because of an ATM mutation. When breast cancer patients are studied, however, they do not have an excess of ATM mutations as compared with people without breast cancer. Therefore, the association between ATM mutations and breast cancer risk remains unclear. Studies are being done to better understand this possible link.

What are the symptoms of A-T?

Symptoms of A-T can develop in early childhood, but may develop later in adolescence or adulthood. Symptoms may include:

Poor balance and slurred speech

Ataxia (lack of muscle control leading to an awkward gait when walking)

Telangiectasias (tiny, red "spider" veins) in the corners of the eyes or surfaces of the ears and cheeks (soon after the onset of ataxia)